I don’t think that the trend started in 2020, but in 2019 with the official release of card variants with Throne of Eldraine, which likely sparked a renewed interest for card collecting based on aesthetics, not only playability. Cards like Shahrazad are now selling for $450 up from its earlier price of $250 not that long ago. The card is banned in every format. Earlier this year Cardkingdom was completely packed with hundreds of Alpha and Beta. It’s all mostly gone now. Also it seems that collectors are not putting much stock into the fact that Unlimited and Revised are two different sets. To them they’re just white bordered. There’s Alpha, then Beta, and then there’s the white bordered. That’s what the prices seem to reflect.

I don’t know why Academy Rector is being held back. I suppose the print run on Urza’s sets were much larger than the “Four Horsemen”. It’s also a little more niche, being a white enchantment card, though I’m not sure that matters in crazy buyout world of 2020.